1. Field of the Invention
The present invention relates to a write inhibit tab of a disc cartridge for protecting stored data by inhibiting to write, and particularly, to the write inhibit tab of the disc cartridge which is provided for both of disc cartridges of a removable disc and an unremovable disc.
2. Description of the Related Art
A disc cartridge for holding a disc, such as a photo-disc, has a write inhibit tab indicating whether the disc may be written or not. FIG. 1 shows a disc cartridge used for the prior art.
In FIG. 1, the disc cartridge 1 is (comprised of upper and lower cases 2 and 3, which are integral with each other. A recording medium of a disc shape (not shown) is rotatably held in the disc cartridge 1. Each of the upper and the lower cases 2 and 3 has a spindle hole 4 and a head window 5, through which an optical beam emitted from an optical pick-up (not shown) irradiates the disc. When the disc is not operated, the spindle hole 4 and the head window 5 are closed by a shutter 6 for preventing the disc from dust or touching. The disc cartridge 1 cannot unload (remove) a disc, because it has no open-close shutter for loading and unloading the disc from the disc cartridge.
When the disc cartridge 1 is installed in a disc driving system, the shutter 6 is slid in the arrow indicated direction for disclosing the spindle hole 4 and the head window 5, then a center hole (not shown) of the disc and a part of the recording medium are exposed.
The write inhibit tab 7 is assembled to the disc cartridge 1 for detecting whether the disc may be written or not. The upper case 2 has a check hole 8 of ellipse, and the lower case 3 also has a check hole 9 of ellipse, positions of which correspond with each other.
FIG. 2 shows a perspective view of a write inhibit tab 7 of the prior art. The write inhibit tab 7 of the prior art is comprised of a main body 10, a column 11, slide parts 12 and 13 of the respective sides of the main body 10. The main body 10 has a small hole 14. The main body 10 further has two elastic juts 15 and 16 extending parallel with each other. At the ends of the elastic juts 15 and 16, there are formed projections 17 and 18.
FIG. 3 shows a magnified view of a holder 19 formed on the lower case 3. The disc cartridge 1 has the holder 19 which is provided for holding and allowing the write inhibit tab 7 to slide in the arrow indicated direction as shown in FIG. 3. FIG. 4 is a perspective view of the holder 19. The holder 19 is comprised of first, second and third walls 20, 21, and 22. The first and the second walls 20 and 21 are formed in parallel, and have slits 23 and 24 respectively for engaging with the projections 17 and 18. The third wall 22 restricts the movement of the write inhibit tab 7. The write inhibit tab 7 is inserted to the holder 19 from the upper direction thereof, as shown in FIG. 4. The write inhibit tab 7 is installed in the disc cartridge 1 by assembling the upper and the lower cases 2 and 3 as one body. The column 11 is inserted to the check hole 9, and the small hole 14 on the main body 10 is visible through the cheek hole 8 of the upper case 2. A vertical movement of the write inhibit tab 7 is restricted by the upper and the lower cases 2 and 3.
The write inhibit tab 7 is displaced manually by inserting a pin into the small hole 14 through the check hole 8 and moving it. The write inhibit tab 7 is tentatively positioned by engaging the projections 17, 18 with the slits 23, 24 or upper ends of the walls 20, 21, as shown in FIG. 3. When the disc cartridge 1 is loaded on a disc drive system, the disc drive system senses the position of the write inhibit tab 7 by a sensing device such as a photo-sensor or a mechanical sensor, and discriminates whether data writing on the disc is possible or not.
Some of the disc cartridges have open-close shutters coordinated with loading and unloading of a disc in disc drive systems. FIG. 5 shows a plan view of the disc cartridge 27 having such an open-close shutter 25. A write inhibit tab of a disc cartridge 27 having the open-close shutter 25 is installed in the shutter 25, for allowing loading and unloading of the disc. A support area 26 of arched shape for supporting an under side of the disc edge, an elastic protrusion 28 for engaging the open-close shutter 25 with a body of the disc cartridge 27, a front cover 29, and a holder 30 for installing the write inhibit tab 7 therein are formed on the open-close shutter 25. The open-close shutter 25 is rotatably supported by a hinge 31. When closed the open-close shutter 25 is contained within the disc cartridge 27 except the front cover 29 which is exposed.
FIGS. 6 and 7 show magnified partial views of the holder 30. The holder 30 has first, second and third walls 20, 21 and 22. Slits 23 and 24 are formed on the first and the second walls 20 and 21 respectively. An elliptical check hole 37 is formed on the open-close shutter 25. The disc cartridge 27 has check holes 8 and 9 on the upper case 2 and the lower case 3 respectively corresponding with an elliptical check hole 37, as shown in FIG. 5. The write inhibit tab 7 is installed in the holder 30 from the upper direction of the open-close shutter 25. When the open-close shutter 25 is contained in the disc cartridge 27, the vertical movement of the write inhibit tab 7 is restricted, which is same to the case of the disc cartridge 1 shown in FIGS. 1 through 4. The write inhibit tab 7 may be displaced manually by inserting a pin into the small hole 14 through the check hole 8 of the upper case 2 and by manually moving it. When the disc cartridge 27 is loaded on a disc drive system, the disc drive system senses the position of the write inhibit tab 7 by a sensing device, and discriminates whether data writing on the disc is possible or not.
As mentioned before, the write inhibit tab 7 of the disc cartridge 27 is installed in the holder 30 from the upper direction of the open-close shutter 25, as shown in FIG. 7. When the open-close shutter 25 is opened for removing a disc from the disc cartridge 27, the write inhibit tab 7 has no restriction in its vertical direction, which may cause that the write inhibit tab 7 may change its position, or may drop therefrom. In this case, the position of the write inhibit tab 7 may change from "writable" to "nonwritable", then, the stored data of the disc which is reloaded thereon may be erased erroneously.
In order to solve the problem, it is conceivable that structures of the write inhibit tab 7 and the holder 30 are changed so as to prevent the movement or drop of the write inhibit tab 7, when the open-close shutter 25 is open. To change the structures of the write inhibit tab 7 and the holder 30 means that they could be used interchangeable with the disc cartridges having no open-close shutter 25, and further means increase of the number of parts of the disc cartridge, of the number of dies for producing the parts and of the production cost.